Drawing instrument



arch 16, 1937.

E. RONNQUIST 2,073,881

DRAWING INSTRUMENT Filed May 28, 1936 2 Sheets-Sheet l f'zyij Patented Mar. 16, 1937 UNITED STATES PATENT OFFICE 4 Claims.

This invention relates to improvements in draftsmens instruments and its object is to provide a parallel ruler that will take the place of the T-square in mechanical drawing; and to provide an instrument that will increase the efliciency of a small drafting board, increasing the utility of the triangle and protractor in connection' therewith.

A further object is to provide a parallel ruler that can be adjusted to any position and locked positively; the ruler, when released, dropping through gravity to the lower edge of the board to instantly provide space for the working of other instruments.

A further object is to provide an efiicient substitute for the T-square that may be permanently secured to the drawing board and moved about therewith without inconvenience, always ready I for instant use.

More specifically the instrument includes a pair of parallel bars connected together by lazy tong bars, one of said parallel bars being movable laterally or transversely of the board while retained at a constant distance from the other so that the triangle, or other instrument, may be used' for workup to each lateral edge -of the board, U 7

With the foregoing and other objects in view the invention consists in the combination and arrangement of parts to be hereinafter fully described, pointed out in the claims and illustrated in the accompanying drawings which form a part of this application for patent and in which Fig. 1 is a plan view of the instrument applied to a drawing board and shown in connection with a triangle, altered positions of the instrument and of the triangle being shown in dotted lines.

Fig. 2 is a vertical sectional view through Fig. 1 on the line 2--2 thereof. a

Fig. 3 is a cross sectional view through Fig. 2 on the line 3-3 thereof.

Fig. 4 is a view in elevation of one roller fastener, the dotted lines denoting the flange formed Fig. 9 is a vertical sectional view, enlarged, through Fig. '7 on the line 9-9 thereof.

Fig. 10 is a view of Fig. 11 in elevation.

Fig. 11 is a top plan view of Fig. 10.

Fig. 12 is a cross'sectional view through Fig. "5 11 on the line l2-|2 thereof.

Like reference characters denote corresponding parts throughout the several views.

The present instrument is designed for use in 1 school classes in mechanical drawing and for use by the professional draftsman. The student will use it most frequently as illustrated in Fig. 1 while the skilled draftsman will also find constant use for it in connection with the protractor as shown in Fig. 7. The instrument includes 5 two identical channel bars or runways I, 2, the channel slot or opening 3 extending longitudinally of each upper face of a bar from end to end, the ends of the runways being open. The base bar or runway I 'is adapted to be secured to the lower edge of the drafting board 4 by brads or fasteners 5 except when it is to be used in con-' nection with the protractor, the heads of said fasteners being disposed within the runways to serve as stops as hereinafter described. Spaced from the fasteners or stops 5 are the inner stops 6, both runways beingprovided with stops 5 and 6. 'The stops of runway 2 aresecured to and carry the rule 1 of materially greater width than the runway but of the same length, the runway extending centrally of the rule so that the lateral edges thereof extend beyond the rule. The rule I is made of a resilient material, slightly raised or arched between its ends so that when disposed upon the drawing board only the ends rest upon the board, the intermediate portions being clear of the board as shown in Fig. 3, to avoid soiling the drawing.

The runways are connected together by the lazy tong bars 8, each end of each bar 8 being 40 mounted to the spur 9 of a roller In, which rollers ID are disposed in the runways. In assembling the instrument the head upon the free end of each spur is formed after the tong bar has been disposed thereupon, the head being formed by application of a small die to the spur. The tongs 8 are secured together centrally by the threaded bolt I I which passes centrally through the corrugated washers' I2, one carried by each tong bar, the corrugations thereof engaging each other as the washers are brought together by means of the wing nut l3 upon the bolt II. By means of this construction the tong bars may be locked together in any adjusted position desired.

The ends of the lazy tong bars are adjustably secured to the runways between the outer and inner stops 5, 6. The runway 2 with rule 1 are full floating and may be adjusted toward or away from the base runway l or laterally so that either end may be disposed beyond the lateral edge of the board, the lateral adjustment being made while the distance between the runways remains constant. This adjustment permits the use of the triangle in the positions at the lateral edges of the board as shown in dotted lines in Fig. 1. As the drawing board is always used in an inclined position with its top edge at an elevation the runway 2 with rule I will instantly drop through gravity to the lowest dotted position when the wing nut I3 is loosened, Fig. 1.

In Fig. '7 the instrument is shown as used with a protractor. The base runway la is not secured by the brads or stops 5, 6 to the board but it is pivotally secured to the board by the bolt l4 that passes through the protractor I5, which latter member is either secured by countersunk fasteners l6 to the board, or a protractor I5a formed with a flange l5b may be secured by spurs I and a screw clamp l! to the board. This type of spur or fastener may be as readily pressed manually into the board or removed therefrom as the ordinary thumb tack so that the protractor is here adapted for instant adjustment to any position about the board desired, such as to one side, one corner, or along the lower edge thereof. The bottom face of the protractor base and the top face of the runway la are formed with corrugated washers I8, superposed, and adapted tobe locked in adjusted position by means of the wing nut [9 of bolt l4.

When this wing nut is loosened the instrument proper may be adjusted relative to the protractor and board, as shown in Fig. '7, and then locked in such position by the wing nut. When the instrument is not in use or when it is to be carried about, the floating runway is disposed in the lowest dotted line position shown in Fig. 1 and the tong bars 8 locked. It is now out of the way, compact and rattle-proof. The stops 5, 6 limit the extent in either direction of the movement of the lazy tong bars.

While the foregoing is the preferred embodiment of the invention it is to be understood that certain minor changes or alterations may be resorted to during the extensive manufacture of the same and reservation is therefore made of all such changes or alterations as rightly fall within the scope of the appended claims.

What is claimed is:-

1. In a drafting instrument, a base runway for fixed application to the lower edge of a drafting board, a full floating arched resilient runway, connection between said runways whereby said full floating runway may be adjusted toward and away from said base runway and adjusted laterally, and a lock interposed in said connection, said full floating runway gravitating toward said base runway when said lock is open and the drawing board in its normal inclined position.

2. In a drafting instrument, in combination with a drafting board, a protractor secured to the drafting board, a base runway, a bolt pivotally securing said base runway to said protractor and the drafting board, means for locking said base runway releasably in adjusted position relative to said protractor, a full floating runway, and means for adjustably connecting said full floating runway to said base runway.

3. In a drafting instrument, in combination with a drafting board, a protractor removably secured to the drafting board, a base runway pivotally secured to said protractor and to the drafting board, means for releasably locking said base runway in adjusted position relative to said members, a full floating runway, and means for adjustably connecting said full floating runway to said base runway.

4. In a drafting instrument, in combination with a drafting board, a protractor removably secured to the drafting board, a base runway, corrugated meshing washers interposed between said base runway and protractor, a bolt pivotally connecting said base runway to said protractor and drafting board, a wing nut for said bolt, a full floating runway, and means for adjustably connecting said base runway and full floating runway, said full floating runway gravitating toward said base runway when the latter and said wingnut are in a predetermined position relative to said protractor.

EDWIN RONNQUIST. 

